How Solid Forms

1. How Solid Forms Chapter 2 Section 3 6th Grade Team

2. Standards • S.6.6.b Students know different natural energy and material resources, including air, soil, rocks, minerals, petroleum, fresh water, wildlife, and forests and know how to classify them as renewable or nonrenewable.

3. Anticipatory Set

4. What is Soil? (Input) • Soil- the loose, weathered material on Earth’s surface in which plants grow. • Bedrock- the solid layer of rock beneath the soil • Once bedrock has been exposed to the surface, it gradually weathers into smaller and smaller particles- soil

5. Soil Composition • Soil is a mixture of rock particles, minerals, decayed organic material, water and air. • Humus- the decayed organic material that is soil • It is dark colored substance that forms as plants and animal remains decay. It contents nutrients and plants get their nutrients from this. As plants grow they absorb humus. • Fertility- of soil is a measure of how well the soil supports plant growth. If it is rich is humus, it has high fertility.

6. Soil Texture • Sand feels course, and clay feels smooth and silky • Soil texture will depend on the size of individual soil particles. • The texture or particle size of soil determines how much air and water the soil can hold. • Clay- has a dense, heavy texture and they hold a lot of water so pants grown in them can “drown” for lack of air • Sandy- has a coarse texture and water quickly drains through it killing the plant from lack of water. • Loam- soil that is made up of about equal parts of clay, sand, and silt.

7. Process of Soil Formation • Soil forms as rock is broken down by weathering and mixes with other materials on the surface. Soil is constantly being formed wherever bedrock is exposed. • Soil horizon- a layer of soil that differs in color, and texture from the layers above it and below it. • Horizon A- topsoil= a crumbly, dark brown soil that is a mixture of humus, clay and other minerals. • Horizon B-Subsoil=consists of clay and other particles washed down from Horizon A but little humus. • Horizon C-contains partly weathered rock

9. Soil Types • Scientists classify the different types of soil into major groups based on climate, plants, soil composition, and whether the soil is acidic or basic. • Hot, Wet climates- fertile soil but rain washes way humus and minerals. Soil formation would take more rapidly with this type of weathering. • Cold, Dry climates- the soil is often very thin • Moderate Temps and Rainfall- thickest, most fertile soil forms

10. Soil Types • The common plants found in a region are used to classify soil • Grassland soil is different from forest soil • Scientists classify soil by it’s composition • Acidic- if a substance reacts strongly with some metals and changes blue litmus paper red • Basic- if a substance feels SLIPPERY and changes red litmus paper blue. • Scientists use the pH scale to measure acidic and basic substances.

11. pH • pH of 0= strongly acidic • pH of 7= neutral • pH of 14 = strongly basic • For plants to grow they need a pH of 6 or 7.5.

12. Living Organisms in Soil • Some soil organisms make humus, the material that makes soil fertile. Other soil organisms mix the soil and make spaces in it for air and water. • Forming Humus • Plants form humus. As plants shed leaves, they form a loose layer of humus • When plants die, they become part of litter • Humus forms in a process called decomposition. • Organisms that live in soil turn deal organic material into humus

13. Living Organisms in Soil • Decomposers are the organisms that break down the remains of dead organisms into smaller pieces and digest them with chemicals. • Soil decomposers- fungi, bacteria, worms, other organisms, mites and worms. • Fungi- mold and mushrooms. They digest and grow on plant remains. • Bacteria causes decay and attack dead organism and their waste in soil

14. Mixing the Soil • Earthworms do most of the work of mixing humus with other materials in soil. • As Earthworms eat their way through the soil, they carry humus down to the subsoil and subsoil to the surface. • Earthworms also pass out the soil they eat as waste • Burrowing animals- mice, moles, prairie dogs, and gophers break up hard, compacted soil and mix humus with it. • Earthworms and burrowing animals also mix air into the soil

15. Checking for Understanding • What is humus? • What happens to a plant grown in clay? • What is the pH of a acid? • What is the pH of a basic • What is the pH of a neutral? • What is a decomposer?